Writing instrument



FIG. 1 is a perspective view of a writing instrument in accordance with a first embodiment of my design;

FIG. 2 is a right side elevational view with the side opposite being a mirror image thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a front view thereof; and,

FIG. 6 is a rear view thereof. 

The ornamental design for a writing instrument, as shown and described. 